The invention relates to automatic power circuit breakers in general and, in particular, to a contact arm latch and trip arrangement used in automatic current limiting circuit breakers to avoid contact reclosure after a rapid repulsion of the contact arms upon occurrence of a short circuit. Automatic current limiting circuit breakers are well known as described for example in U.S. Pat. No. 4,375,021 assigned to the common assignee of this invention. In current limting circuit breakers, means are generally provided to motivate one or both of the contact arms under the action of intense electrodynamic repulsion forces generated by short circuit currents.
This is accomplished by arranging the contact arms rotatable with respect to the circuit breaker support structure and providing the arms with return springs of sufficient force to pass operating current. When a short circuit occurs, the electrodynamic repulsion generated within the contact arms, overcomes the return spring force and rotates the contact arms to open the contacts.
However, under intense electrodynamic repulsion, one or both of the contact arms could strike against the contact arm stops provided within the circuit breaker enclosure and rebound back to carry the contacts into their closed position.
Reclosure of the contacts after electrodynamic repulsion should be avoided in a current limiting circuit breaker since the circuit interruption time must be as short as possible to provide the necessary current limitation.